Donor RBC selection for group A2 (or group A2B) individuals who have anti-A1

A transfusion medicine physician in Massachusetts reports that her hospital transfusion service recently became aware of a group A2 patient whose serum contains anti-A1 and who needs RBC transfusions. The Massachusetts physician was wondering what other transfusion services do in a similar situation. Her staff is creating a new SOP (they do not have one yet) to address donor RBC selection for group A2 (or group A2B) patients with anti-A1. Their first draft includes the following points:

1. Perform reverse (back) type with A1 cells through AHG phase.
2. Confirm A2 (A2B) type with Dolichus biflorus lectin.
3. For Crossmatching:
   1. If anti-A1 reacts at AHG phase then give AHG XM compatible A2 (A2B) RBCs.
   2. If anti-A1 reacts only at Immediate Spin phase then give AHG XM compatible A (AB) RBCs.
4. If unable to find compatible RBCs, give AHG XM compatible group O RBCs with blood bank physician approval.

She would appreciate comments on the above draft protocol.

Editor's comment: Guidance for donor RBC selection for patients with unexpected alloantibodies, including anti-A1 in group A2 or A2B individuals can be found in the Guidelines for compatibility procedures in blood transfusion laboratories by the Working Party of the British Committee for Standards in Haematology Blood Transfusion Task Force (pdf file)

ADDENDA Jan. 10, 2005

The following comments have been received.

1. Ronald E. Domen, MD, Medical Director, Blood Bank and Transfusion Medicine at Penn State Hershey Medical Center in Hershey, Pennsylvania (attribution used with permission) reports that they routinely give group O red cells to those patients with an anti-A1 rather than screen their inventory for A2 red cells. In 1986 Dr. Domen reported a case (in abstract form) of acute hemolysis caused by anti-A1 in an A2 patient (Domen RE, Keehn WH, Calero A. Blood 1986;68(suppl. 1):295a). The anti-A1 was demonstrable at a titer of 1:16, and although reactive at 37 C, it "prewarmed away". The patient hemolyzed 2 units of A1 red cells without significant sequelae.

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